The prior art driving bar has a pivotal portion which make the driving bar bendable to form a multiple folding portion so that the driving bar can be used to driver the screw at some locations which is difficult to be arrived by the general straight driving bar. Since when the driving bar is blended, the arm of force of the driving bar becomes small. This is because that the driving bar is bent to have a rectangular shape. This induces that the force applied to the screwdriver cannot be effectively transferred to the driving head of the driving bar.
In another prior art, the driving bar has two pivotal portions so that the driving bar has two sections which can folded. This design can generate a more effective structure, which causes that the force can be transferred to the driving head with a great arm of force. However this prior art still has the following disadvantages.
The connection between the handle and the driving bar is weak so that it is easily released. Thereby the screwdriver cannot effectively drive a screw. Furthermore, the middle part of driving bar has two pivotal portions which connect the front and distal end of the driving bar. However the pivotal portions generate weak points in driving. Furthermore, the force applied to the screwdriver will disperse in the pivotal portions.